Bristol Palin to Levi Johnston: 'It's Over'

And just like that, they were off again. "It's over. I broke up with him," Bristol Palin tells PEOPLE exclusively of her second try at an engagement to Levi Johnston, father of her 19-month-old son Tripp.

Palin, 19, says the relationship soured on July 14, the very same day they announced their marriage intentions to the world. Palin says he told her that evening he might have fathered a baby with another teenage girl. (Palin did not name the young woman, but a pregnant former girlfriend of Johnston's has since publicly denied his paternity.)

In an emotional phone interview with PEOPLE, Palin spoke through tears about feeling heartbroken, humiliated and trapped – while Johnston acted cool. "There's been no remorse," she says, adding that she's seen him only once in the past three weeks.

"The final straw was him flying to Hollywood for what he told me was to see some hunting show but come to find out it was that music video mocking my family," she says. "He's just obsessed with the limelight and I got played."

Palin's mom, Sarah, the former Alaska Governor and prominent Republican with whom Johnston publicly – and bitterly – sparred over the past year and a half, tells PEOPLE: "I wish for Bristol to be able to move forward in life with her same forgiving, gracious, optimistic spirit, but from henceforth she'll know to trust but verify. Bristol is strong, she is independent, and she knows what is right for her son."

Most immediately, Bristol has decided that what's right for her and Tripp is to vacate the Anchorage townhouse she only bought last February, saying too many photographers and gawkers were hanging around her driveway.

"I didn't feel safe," she says, adding that she's already cleaned out the three-story home and put it on the market. A friend tells PEOPLE she is temporarily staying at her parents' more secluded home about 45 minutes away in Wasilla.

Bristol also says she's not giving up hope of a safe and happy two-parent home for Tripp. "I have faith that I'll find it. Through this whole experience I know I need a man who's going to be completely honest with me and someone who loves me and Tripp and wants to be with him all the time. I also want someone who has religious beliefs and a good family."